Soret扩散对合成气层流火焰速度的影响

本文通过包含详细化学反应机理的数值模拟研究了常温常压和高温高压下Soret扩散对成气预混火焰的影响。研究重点是揭示并解释Soret扩散对合成气/空气层流火焰速度的影响。研究结果表明,合成气/空气层流火焰速度的下降主要是由H自由基的Soret扩散导致的,而H₂分子Soret扩散的影响几乎可以忽略不计。这是因为主反应区和H自由基的Soret扩散是强烈耦合的。由于H自由基Soret扩散流量的增强,Soret扩散对燃烧流量的影响会随着初始温度和压力的升高而增强。     

Improving nonlinearity tolerance of 112-Gb/s PDM OFDM systems with coherent detection using BLAST algorithm

A novel long wavelength photodetector with dual-wavelength spectral response is designed and fabricated using a step-shaped Fabry-Prot (F-P) filter structure.The step-shaped GaAs/AlGaAs distributed Bragg reflectors and the InP PIN photodetector are grown on a GaAs substrate using low pressure metal organic chemical vapor deposition.High quality GaAs/InP heteroepitaxy is realized by employing a thin low temperature buffer layer.The photodetector structure is optimized by theoretical simulation.This device has a dual-peak distance of 19 nm (1 558 and 1 577 nm).The 3-dB bandwidth of 16 GHz is simultaneously obtained with peak quantum efficiencies of 8.5% and 8.6% around 1 558 and 1 577 nm,respectively.     

Comparison of effects of relative carry-envelope phase on two-color few cycle pulses propagating in dense and dilute lambda-type mediums

In this paper we compared effects of relative carry-envelope phase (RCEP) of two-color few cycle pulses on propagation behavior and spectral property under the single-photon resonant condition in the dense and dilute lambda-type three-level atomic mediums. It is found that, in the dense medium, with propagation distance increasing, the compound pulse of the two-color few cycle pulses will split into two or three sub-pulses with different amplitudes and shapes, or does not split, and this is completely determined by value size of RCEP; with value of RCEP decreasing, range and strength of the spectrum (particularly the higher spectral components) increase obviously, the highest frequency is about eight times of the resonance frequency. In the corresponding dilute medium, effect of RCEP on propagating behavior and spectral property is much different from that in the dense medium; specially with value of RCEP decreasing, spectral strength increasing is evident but spectral range not, the highest frequency of the spectrum is only about two times of the resonance frequency.     

德鲁德分布非均匀膜的光学特性模拟分析

从德鲁德理论出发,对多元共蒸法镀制的非均匀膜的折射率分布与沉积速率的关系进行了探讨;然后利用计算机辅助模拟,对德鲁德分布非均匀光学薄膜,从单周期和多周期、正变和负变、完整周期和存在半周期几个方面对其光学特性进行了系统分析.研究发现：其透射率的极小值和周期数的关系遵从周期数的三次多项式衰减规律,不同规律的德鲁德分布非均匀膜可用来设计不同功能的滤光片.     

应用不对称一维光子晶体结构制备窄光谱LED

对周期性的GaAlAs／AlAs模块堆积组成的有缺陷的一维光子晶体的光波传输模式进行了理论与实验研究。由于堆积结构的周期性受到破坏,导致了光子晶体中模密度发生变化,光波的传播也发生了变化。对模密度和光的传播模式分别用流行的光子能态理论和光学传输矩阵进行了计算和模拟。计算发现采用不对称结构的一维光子晶体结构在实际应用中有更大的灵活性。用金属有机物化学汽相沉积方法实现一维光子晶体,并用于裁剪普通的发光二极管电致发光谱,在20mA的激发电流下,半峰全宽为2．8mm,单色性优 于共振腔发光二极管。在较大的激发电流下,带边发射的增强现象也被观测到。     

Study on the Interaction Between Water-Soluble CdTe Quantum Dots and Ovalbumin by Optical Spectroscopy

ABSTRACT

CdTe quantum dots (QDs) modified by 2-mercaptoethylamine hydrochloride (CA) and thioglycolic acid (TGA), respectively, were synthesized in aqueous medium. The interaction of CdTe QDs with ovalbumin has been investigated in depth by Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption, fluorescence-quenching spectrometry, and resonance Rayleigh scattering spectroscopy (RRS). Fluorescence data show that the quenching type of ovalbumin by CA-CdTe QDs is static quenching with the binding constant being 10^?4 M^?1, and the number of binding sites being one. The calculated thermodynamic parameters demonstrate that the main binding forces are hydrophobic interaction and electrostatic attraction. In contrast, the quenching style of ovalbumin by TGA-CdTe QDs is verified to be dynamic quenching. Under suitable acidity conditions, the interaction of CA-CdTe QDs or TGA-CdTe QDs with ovalbumin leads to the remarkable enhancement of RRS, and the increments are found to be proportional to the concentration of ovalbumin in a certain range. A simple and highly sensitive RRS approach for determining ovalbumin is developed. In addition, the causes for the enhancement of RRS and the quenching of fluorescence are investigated to shed light on the quenching mechanism.     

Analyzing Increased Fluorescence of Single Quantum Dots on Dehydrated Agarose by Single-Molecular Imaging

A single-molecule imaging technique was used to study emission behaviors of quantum dots (QDs) on the surface of glass and dehydrated agarose. The luminescence intensity of single QDs on the dehydrated agarose film was 2 or 3 times that on the glass. Our results revealed that the roughness and the hydrophobic nature of dehydrated agarose gel can suppress the blinking of single QDs. A clear decrease in the power law exponent for “on” time but an increase for “off” time was observed when the glass was replaced with 4% and 8% dehydrated agarose. The enhanced luminescence of QDs on dehydrated agarose will make their applications on microarrays more attractive.     

The separability of two-mode Gaussian state under amplification and symmetric damping

The performances of a two-mode Gaussian state under parametric amplification, symmetric amplitude damping and thermal noise are studied. The time-dependent complex correlation matrix of the state in evolution is given. The separability of the final two-mode Gaussian state is examined under symmetric amplification and asymmetric amplification separately.     

[5‐(p‐alkoxy)phenyl‐10, 15, 20‐tri‐phenyl] porphyrin and their rare earth complex liquid crystalline

Three series of porphyrin liquid crystalline compounds, [5‐(p‐alkoxy)phenyl‐10, 15, 20‐tri‐phenyl] porphyrin and their rare earth complexes (Tb (III), Dy (III), Er (III), Yb (III)), with a hexagonal columnar discotic columnar(Col_h) phase have been synthesized. These compounds were characterized by elemental analysis, molar conductances, UV‐visible spectra, infrared spectra, luminescence spectra, and cyclic voltammetry. These compounds exhibit more than one mesophases, which transition points of temperature change from ?33.6 to 16.0 °C, and transition points of temperature for isotropic liquid also increase from 4.9 to 38.2 °C, with increasing chain length. Their surface photovoltage (SPV) response have also been investigated by the means of surface photovoltage spectroscopy (SPS) and field‐induced surface photovoltage spectroscopy (EFISPS). It was found that their SPV bands are analogous with the UV‐visible absorption spectra and derived from the same transition. Copyright © 2007 John Wiley & Sons, Ltd.     

Contracting on Average Random IFS with Repelling Fixed Point

We consider random iterated function systems which consist of strictly increasing and (not necessarily strictly) convex functions on a compact interval or on a half line. We assume that the system is contracting on average in a sense which is wide enough to permit the existence of a common fixpoint at which some functions of the system are expanding and perhaps none of them are contracting (see Fig. 1). We prove that the Hausdorff dimension of any of the possibly uncountably many invariant measures is smaller than or equal to the accumulated entropy divided by the Liapunov exponent. Mathematics Subject Classification. Primary 42A85 Secondary 11R06; 26A46; 26A30; 26A78; 28A80